Thermoplastic storage bags having reclosable fasteners have been in wide use to store various items. One type of bag includes interengagable male and female closure elements or profiles that may be closed by pinching the elements together at one end thereof between a user's finger and thumb and sliding the user's opposed finger and thumb along the elements toward another end of the bag. One difficulty faced by a user of such a bag results from misalignment of the male and female closure elements of the bag as the user is attempting to seal the bag. Often, such misalignment prevents full closure of the bag and typically results in wasted effort and frustration by the user.
Attempts have been made over the years to provide a structure that facilitates closing of a bag by a user. An example of such a structure comprises a guide rib disposed on each side of the closure elements and extending parallel thereto. The guide rib(s) guide the user's finger and thumb as the user is attempting to close the bag so that the incidence of closure element misalignment is minimized.
Kamp U.S. Pat. No. 4,306,924 discloses an apparatus for producing a plastic container having occludable closure strips. The closure strips are supplied from a supply source and fed to a control roll, wherein the control roll in turn feeds the closure strips to an optional heating means that preheats a base portion of the closure strips. The closure strips are then transferred to a rotating casting cylinder having a pair of spaced apart circumferential grooves. The closure profiles are disposed in the grooves of the casting cylinder as the casting cylinder rotates and plastic film is extruded onto the casting cylinder to produce a plastic film with integral closure profiles.
Zieke et al. U.S. Pat. No. 4,741,789 discloses a method and apparatus for applying a profile and adjacent ribs to a traveling film web. The method comprises the steps of drawing a web of bag film over idler rolls into a forming and joining station. The forming and joining station includes a hopper for receiving plastic material, a body with heating means for heating and melting the plastic material and a screw auger for advancing the molten plastic material to a die block. The method further comprises the steps of applying a base member to the film by means of a polytetrafluorethylene-coated lay-on roller and extruding a male profile member, a first rib member and a second rib member as separate extrudates on a bag film web.
Geiger et al. U.S. Pat. No. 4,755,248 discloses a method and apparatus for producing a reclosable bag film. The method comprises the steps of drawing a film web from a die block around a driven rotatable casting roll and passing the film web over idler rolls to a closure member extrusion and joining station. A female profile is extruded from a first extruder and a male profile is extruded from a second extruder onto the film web as the film web passes around an idler roll at the station. The method further comprises the step of passing the film web and profiles around a chilled casting roll to cool the film web and profile.